Arch reconstruction

[flatpan]

We are going from a 3x7 flat panel to a 3.5x12 drop glue/finishing pan. The arch is in need of reconstruction. I understand that there are some older posts on the subject buy looking for additional ideas.
My thoughts are to use 2 inch ceramic blanket.
1. How doespecially one attach the blanket to the arch?
2. Should rigidizer be used to stiffen the Blanket?

The plan is the fire brick the fire box. My thought is to use channel iron to hold the fire brick in place which would allow for easier replacement of bricks and eliminate mortaring. Has anyone tried this approach? Thoughts on pros or consider to this procedure?
Thanks.

[optionguru]

I welded bolts to the arch and pushed the blanket down over it then used large washers and nuts to hold it in place. You can use a little refractory cement to make the bolt head and nut last longer.

[motowbrowne]

The blanket is good stuff. Cheap online too. http://mcgillswarehouse.com/hf11-ceramic-fiber-blanket-1in-8lb-ft3-or-128kgm3-h1cf2cf3c

I've only used 1" blanket, but 2" would only be better. I'm installing a new arch this year also. I'll be using 1" blanket behind my firebricks in the firebox and then some in the back near the flue opening. My rig if a raised flue, though, so it's a bit different. Rather than insulate the whole arch, I'll be filling out with vermiculite which is a good insulator and fills the space forcing the flue gas into the flues. In my experience, there's no need to hold the blanket in place. Just cut the pieces you need a little oversized and stuff it into place. The bricks will hold it in the firebox. In the rest of the arch, there's nothing trying to move it.

My arch uses a piece of angle iron at the bottom of the bricks for the first course to rest on. Be warned, anything other than cast iron is prone to warping.

[wiam]

I built my oil arch last year. The sheet panels are 16 gauge. I drilled through from outside and used 3/8" stainless bolts with fender washers on inside of insulation.

[DocsMapleSyrup]

I built my arch last year and welded nuts under the top rail. The plan was to cut threaded rod, screw it into the nut and push the blanket over the threaded rod followed by a SS washer and nut, so if I had to replace the threaded rod, all I would have to do was to unscrew it from the nut under the ceramic blanket and replace it. I found out that when I used 1" ceramic blanket on the sides of the arch, I did not need anything to hold the blanket in place. It hasn't moved and is holding up well. I used firebrick splits for the sides of the fire box. The only place I did need to anchor the ceramic blanket was the door and at the smoke stack plate. Here's a couple of photos. Also, I found that if you put several nuts on threaded rod, it is easy to tack weld the nuts to the door. I hope the photos explain this better than I did.

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[flatpan]

Thanks for the input.
What are the thoughts on the rigidizer to protect and extend the life of the banket? Is a 2 inch blanket over kill?
If small channel were used alone the fire brick what is the likelihood of warping? Would using refractory mortar over the angle iron reduce the chance of warping?

Will the weight of the fire brick compress the blanket? If i do not use metal to hold the fire brick in place I would assume that they would need to be mortared in place?

Is there a way to insulate the doors!

[flatpan]

Thanks for the input.
What are the thoughts on the rigidizer to protect and extend the life of the banket? Is a 2 inch blanket over kill?
If small channel were used alone the fire brick what is the likelihood of warping? Would using refractory mortar over the angle iron reduce the chance of warping?

Will the weight of the fire brick compress the blanket? If i do not use metal to hold the fire brick in place I would assume that they would need to be mortared in place?

Is there a way to insulate the doors!

[flatpan]

The doors are cast. May need a different approach than shown on Chad's post. I plan to put the arch in the shop tomorrow and studying the project.

[motowbrowne]

The bricks will compress the blanket. From what I hear, it'll be fine. I'm buying 8# density versus 6# density to try to combat the compression. Yes, I think 2" blanket is overkill, but hey, other than costing a little more, I don't think that's a bad thing. I have no thoughts on rigidizer. I don't think it's needed. You don't need to insulate the doors (I'll assuming they're cast iron) you can if you want, though. The picture next to my name is the cast iron doors of my arch glowing red hot. Obviously they waste heat, but I haven't figured out a good way to insulate them. I've thought about adding some blanket to the inside, but you'd have to braze on some threaded rod or little spikes to stick it on. It'd get pretty trashed by firewood as you're firing, but it's cheap enough to replace twice a year even. Would be nice not to start your pants on fire...

The channel iron will probably warp unless it's supported by running pieces down to the ground.

[psparr]

I have a steel door. I cut a piece of blanket to fit it the take some sheet metal the same size and use self drilling screws to fasten it. The sheet metal takes the beating. Only lasts a couple years, but works well

[Super Sapper]

If you have to work on the evaporator already you can build new air tight steel doors for it. There are some threads on here from people who made new doors.

[DocsMapleSyrup]

Flatpan

I have 2" of ceramic blanket in my arch; however, I used 2 - 1" blankets to overlap any seems. My front arch is made of 3"x3"x1/4" steel tubing and was not insulated; however, all the welds broke due to heat, so I put 1" of insulation over it. I don't think that 2" of insulition is overkill. The firebrick will not compress the blanket on the sides of the arch. In the back of the arch, I have 2" of insulation on the floor of the ramp portion of the arch. I do not put blanket in this area. The door blanket is fine after one year. I don't know anything about rigidizer. Any exposed angle iron will warp if not covered with insulation. I would be concerned about mortar as it will hold heat and eventually will get up to the heat you are firing in the firebox. Last year, I did not motar the firebrick and had some of the splits fall down repeatedly, so I motared the bricks in this year.

[flatpan]

I found some 1" ceramic fiber board which I am thinking of using in the firebox instead of the blanket. I thought it may be easier to get the fire brick to hold to the board. How much different is the insulation value from the blanket to the board?
I have one area of concern and that is where the gratesame sit in the back. The front is premanufactured cast iron with factory doors so that will not be a concern. The back of the grates sit on 2 inch angle iron which is doubled up with vertical bracing down to the bottom of the frame. Will this be enough to eliminate 7the chance of warping? I hade a chance to look at an old Small Brothers arc this has notched fire brick on which the grates sit. I had quite a bit of welding already done prior to looking at that one. Is this common? It seems like a good way to protect the iron. Is there any way to insulate the angle iron? Or will that not be needed with the vertical bracing? Keep your input coming ito has been helpful. I may try to get some pictures of what I'm working with posted.

[DocsMapleSyrup]

Flatpan

When I was researching the trader and sugarbush, those who used fiber board said that after a year or two, the board had disintegrated and fell apart. It stayed in place as long as it was not moved. That is why I went to ceramic blanket. The bricks sit on tope of each other and with a little mortar, are quite rigid.

With regards to the firebox floor. As long as the angle iron is placed so that it forms a "V" rather than the other way, ash will fill the "V" and insulate it so there aren't warping problems. You will have warping if it is placed the other way. Many posts I read while doing my arch commented on this.

[motowbrowne]

In my searching recently, the ceramic board was about 4X the price of blanket. That's why I went to blanket.

[flatpan]

If I go with the 2 inch blanket what thickness fire brick should be used? Looks like the options locally is 1-1/4" and 2-1/2".

[motowbrowne]

If I go with the 2 inch blanket what thickness fire brick should be used? Looks like the options locally is 1-1/4" and 2-1/2".

Those are the two common sizes. Split brick and full brick. Do you have bricks already? Personally, my experience with split brick is that it's less than half as durable. Full bricks rarely break. Maybe I was doing something wrong, but I replaced several broken split bricks in my 2x10.

I'm just guessing here, but I imagine that your rig came with full sized bricks. If I were you, I'd be using fill sized bricks, especially if I could reuse the ones I had. Bricks aren't cheap. If using 2" and full bricks takes up too much of your firebox, I'd be rethinking the 2".

[Dale Sparrow]

Nice build Chad!

[DocsMapleSyrup]

Thanks. I'm hoping for a little more efficiency this year.

[n8hutch]

If I go with the 2 inch blanket what thickness fire brick should be used? Looks like the options locally is 1-1/4" and 2-1/2".

I used splits up by the rails and full brick for the rest of the firebox, the split bricks really don't get any abuse up at the top of your fire box. I have 2" of insulation in my whole arch, 1 each of ceramic blanket & arch board.works great only downside is the only warm place in the shack is bye the smoke stack.

[motowbrowne]

only downside is the only warm place in the shack is bye the smoke stack.

I know how that goes. My 2x10 hardly wasted any heat. Pretty much the only place keep warm was by the doors to the firebox. Fine for me, but when i had guests, it was very difficult to keep them out of my way. I think I need install a woodstove in the shack.

[flatpan]

Okay, the arch is basically completed. I purchased 1" ceramic board in the firebox and the area beneath the finishing pan. I will be covering this with full firebrick mortared together with refractory cement once I have moved the arch from the shop to the Sugar Bush.

Is there a way to tie the ceramic board back to the metal on the arch? Is this necessary? Will the refractory cement be sufficient to hold the firebrick to the ceramic board? Or is there a trick to holding these together. The may stay because of the slope on the side of the arch but I'm concerned due to the beating the firebox takes.

Any insights would be helpful.